Angkor

Angkor Wat

I saw a NOVA last night on TV (only dozed for a few minutes :), here it is on Youtube:

https://www.youtube.com/watch?v=QADE8CkEVCw

The program was on the enormous ancient city of Angkor in Cambodia. It was a very interesting show explaining the rise and abandonment of Angkor. Angkor Wat is only one of the hundreds of temples in Angkor the city.

I thought that the LIDAR usage was really amazing, it penetrates the overgrowth and gives a sense of what the city must have been like. The whole city is built on a flood plane which regularly has standing water so the houses of Angkor residents were built on mounds (visible on LIDAR).

the Angkor Wat temple in white

The other thing I didn't realize was that since the big temples in Angkor can't be built on actual bedrock the builders used a couple of techniques to get around the lack of a solid foundation. First while the outside cladding of the temple was sandstone the main structure is of a more porous stone called laterite that is much lighter thus reducing the foundation load. Second, the builders dug down to the underlying soil, compacted it (during the dry season ?) and then added a layer of fine sand (shown in purple):

The sand was then covered with a foundation of the porous laterite stone: The sand layer would become damp due to the moats employed. While dry sand is NG for building: